KATYDIDS AND
TERMITES:
PLANKTON
AND TOPSOIL
OF
A RAINFOREST
David A. Nickle
James L. Castner
T
HE METAPHORIC TITLE OF THIS PAPER DESCRIBES A
functional relationship between two target
groups of insects and a very well-known,
yet poorly understood,
ecosystem, the tropical
rainforest. This is an overview of our research on
the biodiversity of New World Tettigoniidae and
Isoptera. We also describe the impact these two
groups have had on global resources and suggest
ways in which tropical biodiversity studies can be
applied not only to systematics but to environmental conservation issues as well.
Since 1986, we have been involved in an intensive biodiversity study in northern Peru, leading
groups of volunteers to investigate the diversity of
katydids
and related
insects in Amazonian
rainforests near Iquitos. The project, Katydids of
Northern
Peru, is funded
by Earthwatch
(Watertown, MA), an organization that provides
field researchers with individuals who are interested in volunteering their time to help scientists do
research. To date, we have received the help of nearly
400 volunteers. Each year teams of up to 15 vol-
AMERICAN
ENTOMOLOGIST
•
Volume 45, Number 4
unteers have worked with us for two-week periods, collecting insects, preparing them for museum
studies, and accumulating
data on the behavior
and biology of katydids and related insects. Although the project focuses on katydids, in reality
our study has involved other orthopterans,
including grasshoppers, locusts, crickets, and mole crickets, and closely related taxa such as walkingsticks,
mantids, cockroaches, and termites. The study also
has expanded to include relationships between faunas of rainforests and those species associated with
rangeland, agroecosystems,
and other local areas
modified by man. Early in our project, it became
evident that katydids and termites were significant
elements in the rainforest ecosystem. Both groups
are primary consumers as well as sources of food
for other animals. Katydids are medium to large
insects that form a significant portion of the overall biomass of the community. In the area we studied, katydids were found to be an important component in the food chain; nearly every animal that
feeds on insects feeds on katydids. They are food
245
for many vertebrates, including birds, monkeys
(particularly
tamarins and marmosets),
rodents,
bats (especially leaf-gleaning species), marsupials,
lizards, snakes, frogs, toads; and invertebrates such
as spiders, centipedes, amblypygids, ants, wasps,
bugs, and even other katydids. Termites also serve
as food for fish, amphibians, lizards, birds, mammals, ants, spiders, and bugs, several of which feed
on termites almost exclusively. Furthermore,
termites are important
decomposers.
Soils in
rainforests tend to be nutrient poor, with little or
no topsoil components.
By fragmenting
and digesting dead leaves, fallen trees and branches, and
other decaying vegetation, termites make available
the nutrients tied up in this vegetation by returning
the nutrients to the soil. This is accomplished by
the enterofauna
and flora within their digestive
systems. With these associated symbionts, termites
also can convert atmospheric nitrogen into a form
that is usable both by themselves and other organisms (Benemann 1973, Breznak et al. 1973). Termites use the fixed nitrogen for their own growth;
surplus nitrogenous material is excreted, becoming available to plants in the community. Nutrients
are redistributed
in soils through the actions of
many species. Other soil properties also are affected
by the action of tunnelling and nest building activities of termites.
Fig. 1. Pterochroza ocellata (L.), largest of the Peruvian leaf
mimicking katydids. [Photograph courtesy of James L. Castner.]
Fig. 2. Acropsis
tectiformis (Brunner von
Wattenwyl), one of the
180 species of
phaneropterine katydids
occurring in the forest
canopy of rainforests in
northern Peru.
[Photograph courtesy of
James L. Castner.]
Katydids
Table 1. Diversity of tettigoniid fauna from four geographic regions
USA
(Poole and
Genrili
Subfamily
1992)
Panama
(Nickle
and
Collins
Costa Rica
(Naskrecki,
personal
communication)
Peru
(Nickle,
unpublished
data)
1992)
Conocephalinae
41
3
5
3
Copiphorinae
24
24
52
60
Listroscelidinae
2
7
4
20
Phaneropterinae
56
71
100
179
6
58
113
117
163
274
379
Pseudophy llinae
Tettigoniinae
134
Total
263
246
Katydids (Tettigoniidae) are a diverse group of
medium to large insects closely related to crickets.
In the United States, there are 263 species (Poole
and Gentili 1997) whereas in Panama, a tropical
country less than one-hundredth
as large, there
are more than 160 species (Nickle 1992). The number of species in Costa Rica-a
country comparable in size but more diverse in geographic habitats than Panama-is
reported
to be 274
(Naskrecki,
personal
communication).
In our
study, we have identified 379 species from three
forests separated from one another by a distance
of no more than 65 kilometers (Nickle 1988, Nickle
and Castner 1995). It is perhaps the richest fauna
of tettigoniids in the world. Five subfamilies are
known from these regions: Pseudophyllinae (woodland katydids!) (Fig. 1); Phaneropterinae
(bush
katydids!) (Fig. 2); Copiphorinae sensu lata (coneheaded katydids1, including Copiphorinae
sensu
stricto and Agraeciinae); Listroscelidinae (predaceous katydids!); and Conocephalinae
(meadow
katydids!) (Table 1).
Although this fauna is rich and diverse, nothing was known before our study of the behavior
and habits of the various taxa. Nearly all of our
knowledge of these insects was based on temperate
species from the United States, Europe, and Australia (see general reviews of Belwood 1990, Nickle
'Common name nor currently among common names of insects and related organisms approved for use by the Entomological Society of America Committee on Common Names of Insects.
AMERICAN ENTOMOLOGIST
•
Winter 1999
Fig. 3. Staff member Jon
A. Lewis (Systematic
Entomology Laboratory,
USDA, Washington, D.C.)
at work in the rainforest,
sampling a nest of
Nasutitermes species.
1992, and Nickle and Naskrecki
1997). To
evaluate the diversity of behaviors of the insects in
our Peruvian study, volunteers observed the feeding habits, range of nightly movements, and diurnal resting locales over periods of several consecutive nights of individuals of more than 40 species
of katydids. Based on more than 2,000 hours of
observations on diurnal roosting behavior of these
species, and extrapolating
that information to include all related species of this study site, we concluded that 72 % of the 379 species exhibited color
generalism (i. e., insects that are leafy green or deadleaf brown in color but do not strongly resemble
actual leaves) (208 green, 46 brown, and 19 with
both green and brown morphs) [Fig. 2], 14%
showed a more refined level of camouflage (2 wasp
mimics, 5 bark mimics, 13 twig mimics, 29 leaf
mimics [Fig. 1],4 lichen mimics), 5.0% concealed
themselves from view during the day within vegetation and debris, and 9.1 % could not be categorized because of insufficient
data (Nickle and
Castner 1995). Most species with generalized color
patterns were phaneropterines,
most of those species with more specialized primary defenses of mimicry and concealment were either phaneropterines
or pseudophyllines,
and most species with specialized secondary defenses (e.g., biting, kicking, excessive
spines)
were
listroscelidines
and
copiphorines. In addition, all species that concealed
themselves in vegetation and debris were observed
returning just prior to dawn to the same site for up
to 22 consecutive days.
Different species of katydids do not all behave
the same but utilize different methods for avoiding
visually-orienting
predators.
This
became
signifi-
cant in a later study involving feeding behavior of
sympatric tamarins (Nickle and Heymann 1995).
Katydids and related insects are an important component in the diets of mustached
(Sanguinus
mystax mystax Spix) and saddle-backed tamarins
(Sanguinus fuscicollis nigrifrons Spix). Based on
data of captured prey (81 samples, 46 species), we
demonstrated for the first time that these two species of tamarins partition the limited food resource
provided by orthopterans;
this may be one of the
reasons why these two species are able to coexist
sympatrically. Of the katydid species captured, only
three were shared by both tamarin species. Saddlebacked tamarins appeared to specialize more on
understory
species (0-4 m), concentrating
on
pseudophylline
katydids. Mustached tamarins included a greater percentage of phaneropterine
katydids from the lower to middle canopy (4-20 m)
in their insect diet. Although both species of tamarins fed primarily on prey species that were exposed to view during the diurnal feeding period,
only the saddle-backed
tamarin also fed on katydids that spent the day concealed from view within
dead curled leaves. We suspect, but have not yet
investigated, that other predators also may specialize on different kinds of katydids in similar ways,
which may account for similar degrees of diversity
among other organisms within this ecosystem.
AMERICAN
ENTOMOLOGIST
•
Volume 45, Number 4
Table 2.
Family
Diversity
North
America
(Nickle and
Collins,
unpublished
data)
of termite
Panama
(Nickle
and
Collins
fauna
from four geographic
Guyana
(Emerson
1925)
1992)
Peru
(Nickle,
unpublished
data)
regions
Mato Grosso,
Brazil
(Mathews
1977)
Hodotermitidae
3
Kalotermitidae
53
14
]5
2
2
Rhinotermitidae
]6
6
12
9
6
Termitidae
53
25
34
61
84
140
45
61
72
92
Total
Termites
We initiated a secondary project evaluating the
termite fauna in Peru. Nests were sampled repeatedly over a la-year period (Fig. 3), and, to date, we
have collected nearly 1,800 samples of more than
70 species of termites. This represents a rich fauna
compared to other regions. Table 2 shows the results of faunal studies of other regions; continental
North America has 140 species (Nickle and Collins,
unpublished data); the State of Mato Grosso, Brazil, 92 species (Mathews 1977); Panama, 45 species (Nickle and Collins 1992); and Kartabo,
Guyana, 61 species (Emerson 1925). In our Peruvian project, we have collected all castes of most of
the Peruvian species as well as termitophiles and
other insects associated with them in their nests.
247
This collection is one of the most comprehensive made in a Neotropical region, based on numbers of species and numbers of individuals of each
caste represented in each sample.
Most of the species we collected were found
within the rainforest, and we have found that most
were highly dependent on the rainforest ecosystem
for their survival. In cleared areas (rangeland,
farmed areas, and open fields), we collected only
5-6 species of Nasutitermes,
one species of
Heterotermes, one species of Coptotermes, and one
species of Cryptotermes (Nickle, unpublished data).
These species tend to be more tolerant of desiccation than those species living in moist forest environments (Collins 1969). A major problem with
clearing large areas of rainforest is the potential for
the widespread elimination of populations of the
humus-feeding termite species that provide primary
plant
nutrients.
Continued
destruction
of
rainforest environments could lead to local or total extinctions of those species upon which the
rainforest depends for regeneration
(Nickle and
Collins 1992).
The following bleak scenario of rainforest destruction and reforestation and the resulting effect
on the resident
isopteran fauna is very possible:
(1) with the elimination of the shading effect of the
rainforest canopy, termite nests sensitive to direct
sunlight and its excessive heat will become endangered or destroyed within a short time; (2) reproductive success of surviving colonies will be jeopardized when heat sensitive winged reproductives seasonally emerge to reproduce; if they also die or are
stressed in exposed areas, new colonies will not
succeed, the region will have a depauperate termite
fauna, and the supply of nutrients for plant growth
will be reduced greatly or lost; and (3) continual
exposure of the soil to direct sunlight and the
overutilization
of what is left of the scant topsoil
eventually will result in the development of an impenetrable hardpan and desertification
of an already fragile environment.
The annual rate of rainforest loss is becoming a
global concern; more than 76,000 square kilometers (27,000 square miles) are lost annually, and
more than 40% already has been destroyed on a
worldwide basis (Gradwohl and Greenberg 1988).
The tropical rainforest represents an important
and diverse ecosystem, vital to the rest of the world,
with a tremendous impact on global weather conditions, food, pharmaceutical
products, and timber industries; yet we know little of the functional
relationships of its faunal and floral components.
Although seemingly remote from agriculture in
the United States, Amazonian rainforests playa
vital role in the overall growth and well being of
our agricultural
and forestry network. We have
begun to record the termite fauna in the upper
Amazonian region of Peru; many of the species
may have an important future bearing on the protection of rainforest habitats.
We suggest that potential problems for future
reforestation projects could take several forms: (1)
248
without information
on the forest successional
development, it will be difficult to develop successional plantings that would take hold; this is exacerbated by a total absence of a protective canopy
for heat- and light-sensitive young plants; (2) in
the absence of important humivorous termite species, the production of recycled nutrients may be
aborted; and (3) the slow migration of katydids
and other potential prey into new habitats may
result in a scarcity of the foods that introduced
vertebrate species (e. g., monkeys and birds) evolved
to exploit, causing unforeseen failures to repopulate new forests with native fauna.
We see biodiversity studies as being more than
just a series of exhaustive species lists. When combined with the knowledge derived from studies on
the behaviors of these insects, the faunal diversity
of an ecosystem eventually may be applied by humans to their advantage, providing there is enough
time to gather this knowledge and learn how to use
it.
Acknowledgments
Funding for the Earthwatch Project [D.A.N. and
].L.C.] was provided by Earthwatch, Watertown,
MA (Project numbers 87-008, 89-163, 90-010,
91-174,91-015,92-032,94-001,95-001,
and
96-001). Thanks are extended to Piotr Naskrecki,
Department of Ecology and Evolutionary Biology,
University of Connecticut,
Storrs, for providing
information
on the Costa Rican fauna. The following individuals gave us valuable suggestions by
reviewing the manuscript: S. K. Gangwere, Wayne
State University, Detroit, MI; and M. A. Solis and
D. R. Smith, Systematic Entomology Laboratory,
Washington, D.C.
References Cited
Belwood, J. J. 1990. Anti-predator defences and ecology of neotropical
katydids,
especially the
Pseudophyllinae, pp. 8-26. In W. J. Bailey and D.C.F.
Rentz [eds.], The Tettigoniidae: biology, systematics and evolution. Springer. Berlin, Germany.
Benemann, J. R. 1973. Nitrogen fixation in termites.
Science 181: 161-165.
Brcznak, J. A., W. J. Brill, J. W. Martins, and H. C.
Coppel. 1973. Nitrogen fixation in termites. Nature 244: 577-80.
Collins, M. S. 1969. Water relations in termites, pp.
433-458. In K. Krishna and F. M. Weesner [eds.],
biology of termites, vol. 1. Academic Press, New
York.
Emerson, A. E. 1925. The termites of Kartabo, Bartica
District, British Giana. Zoologica 6: 291-459.
Gradwohl, J., and R. Greenberg. 1988. Saving the
rainforests. Earthscan Publications, Ltd., London.
Mathews, A.G.A. 1977. Studies on termites from the
Mato Grosso State, Brazil. Academia Brasileira de
Ciencias, Rio de Janeiro.
Nickle, D. A. 1988. Preliminary results of faunal studies of the orthopteroid insects of the Peruvian Amazon. Metaleptea 10: 25-44.
Nickle, D. A. 1992. Katydids of Panama (Orthoptera:
AMERICAN
ENTOMOLOGIST
•
Winter 1999
Tenigoniidae).
pp. 142-184. III D. Quintero
and A.
Aiello [eds.], Insects of Panama and Mesoamerica,
selected studies. Oxford University Press, London.
Nickle, D. A., and J. L. Castner. 1995. Strategies utilized by katydids (Orthoptera:
Tettigoniidae) against
diurnal predators in rainforests of northeastern Peru.
J. Orthoptera Res. 4: 75-88.
Nickle, D. A., and M. S. Collins. 1992. The termites of
Panama (lsoptera),
pp. 208-241. Til D. Quintero
and A. Aiello
[eds.],
Insects
of Panama
and
mesoamerica,
selected studies. Oxford University
Press, London.
Nickle, D. A., and E. W. Heymann. 1995. Predation on
Orthoptera
and other orders of insects by tamarin
monkeys, Saguillus mystax mystax and Saguillus
fuscicollis Iligrifrolls (Primates: Callitrichidae),
in
northeastern
Peru. J. Zool., London 239: 799-819.
Nickle D. A., and P. Naskrecki. 1997. Recent developments in the systematics
of Tettigoniidae
and
Gryllidae,
pp. 5-40. III S. K. Gangwere,
M. C.
Muralirangan,
and M. Muralirangan
[eds.], The
bionomics of grasshoppers,
katydids and their kin.
Poole, R. W., and P. Gentili [eds.), 1997. Nomina Insecta Nearctica. A check list of the insects of North
America.
Entomo!.
Information
Serv., Rockville,
MD.
Musin s
David A. Nickle is a research Entomologist with
the Systematic Entomology Laboratory, USDA,
ARS, PSI. His research includes systematics
and behavior of Orthoptera,
Isoptera,
and
Thysanoptera.
Together with James Castner,
he has conducted research on katydids, grasshoppers, and termites of the Peruvian Amazon Basin since 1986 and is now developing a
research program on another group of insects,
the thrips. James L. Castner is an adjunct professor Biology at Pittsburg State Universityand
a member of the Scientific Advisory Board of
the Amazon Center for Environmental Education and Research (ACEER). He has made more
than 50 trips to the New World tropics, concentrating on the Amazon basin. His research
interests include visually-oriented
insect defense mechanisms and the biology and ecology
of
the
leaf-mimicking
katydids
(Tettigonidae: Pterochrozini). He currently creates and publishes books and other educational materials dealing with neotropical flora
and fauna. His book, Amazon Insects- A Photo
Guide (Feline Press), is due out in the spring.
•
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249